AP EAMCET2009Chemistrys Block Elements
Assertion (A) K, Rb and Cs form superoxides. Reason (R) The stability of the superoxides increases from ' K ' to ' Cs ' due to decrease in lattice energy. The correct answer is
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is not true
- D(A) is not true but (R) is true
Correct answer
C. (A) is true but (R) is not true
Step-by-step solution
Superoxides are the species having an O - O bond and O in an oxidation state of - 1 2 (superoxide ion is O ₂⁻ ). Usually these are formed by active metals such as KO ₂, RbO ₂ and CsO ₂ . For the salts of larger anions (like O ₂⁻ ), lattice energy increases in a group. Since, lattice energy is the driving force for the formation of an ionic compound and its stability, the stability of the superoxides from ' K ' to 'Cs' also increases.